1. Field of the Invention
The present invention relates to a guidewire having marker bands strategically placed along a distal portion of the guidewire. More specifically, marker bands having the same precise width are placed at varying distances on and along the distal portion of the guidewire whereby the marker bands and the distance between adjacent marker bands can provide a scaling function to enable a physician to gauge fairly accurately the length of an area of stenosis in a blood vessel and to gauge fairly accurately the reduced diameter of the passageway through the area of stenosis.
2. Description of the related art including information disclosed under 37 CFR .sctn..sctn. 1.97-1.99
Heretofore, various guidewires with markers have been proposed. Examples of several previously proposed guidewires with markers are disclosed in the following U.S. Pat. Nos:
______________________________________ U.S. Pat. No. Patentee ______________________________________ 4,957,110 Vogel et al. 5,084,022 Claude 5,114,401 Stuart et al. 5,174,302 Palmer 5,253,653 Daigle et al. 5,267,574 Viera et al. ______________________________________
The Vogel et al. U.S. Pat. No. 4,957,110 discloses a steerable guidewire having electrodes for measuring vessel cross-section.
The Claude U.S. Pat. No. 5,084,022 discloses a graduated guidewire having spaced indicia to indicate the distance that the guidewire is extended into a vessel of a vascular system.
The Stuart et al. U.S. Pat. No. 5,114,401 discloses a guidewire having marks thereon that are used to establish, and maintain as constant, the position of a guidewire in a vascular system. The markings are uniformly spaced along a guidewire having a J-shaped distal end.
The Palmer U.S. Pat. No. 5,174,302 discloses a guidewire with spaced, highly radiopaque regions including radiopaque bands. The bands are located at spaced locations to provide a reference to a physician for positioning the guidewire and a balloon thereon.
The Daigle et al. U.S. Pat. No. 5,253,653 discloses a fluoroscopically viewable guidewire for catheters which includes a core wire having a reduced-in-diameter distal end portion that extends to a rounded distal tip member. A coiled spring wire extends from a larger-in-diameter portion of the coiled wire to and is fixed to the distal tip member in a distal region of the guidewire. Mounted on the reduced-in-diameter distal end portion of the core wire are spaced apart rings or discs which are highly radiopaque forming markers. The markers are arranged in a predetermined spaced relation. In one embodiment, the spacing between the markers is approximately 1 cm.
The Viera et al. U.S. Pat. No. 5,267,574 discloses a guidewire including a core wire having between three and nine marker bands thereon located just proximal of a coiled wire spring tip. The marker bands are placed between one and three centimeters apart along a tapering portion of the core wire.